1. Field of the Invention
The present invention relates to fibre channel systems, and more particularly, to improving power control in fibre channel systems.
2. Background of the Invention
Fibre channel is a set of American National Standard Institute (ANSI) standards, which provide a serial transmission protocol for storage and network protocols such as HIPPI, SCSI, IP, ATM and others. Fibre channel provides an input/output interface to meet the requirements of both channel and network users.
Fibre channel supports three different topologies: point-to-point, arbitrated loop and fibre channel fabric. The point-to-point topology attaches two devices directly. The arbitrated loop topology attaches devices in a loop. The fibre channel fabric topology attaches host systems directly to a fabric, which are then connected to multiple devices. The fibre channel fabric topology allows several media types to be interconnected.
Fibre channel is a closed system that relies on multiple ports to exchange information on attributes and characteristics to determine if the ports can operate together. If the ports can work together, they define the criteria under which they communicate.
In fibre channel, a path is established between two nodes where the path's primary task is to transport data from one point to another at high speed with low latency, performing only simple error detection in hardware.
Fibre channel fabric devices include a node port or “N_Port” that manages fabric connections. The N_port establishes a connection to a fabric element (e.g., a switch) having a fabric port or F_port. Fabric elements include the intelligence to handle routing, error detection, recovery, and similar management functions.
A fibre channel switch is a multi-port device where each port manages a simple point-to-point connection between itself and its attached system. Each port can be attached to a server, peripheral, I/O subsystem, bridge, hub, router, or even another switch. A switch receives messages from one port and automatically routes it to another port. Multiple calls or data transfers happen concurrently through the multi-port fibre channel switch.
Fibre channel switches use memory buffers to hold frames received (at receive buffers) and sent across (via transmit buffers) a network. Associated with these buffers are credits, which are the number of frames that a buffer can hold per fabric port.
Fibre channel switches can have varying number of ports (for example 8, 16 and/or 20 ports). However, all the ports may not be used at a given time depending upon fabric topology or network needs. Power consumption for these switches can also vary depending upon the number of ports.
Conventional fibre channel systems do not have a uniform power consumption control mechanism that will allow a user to use a single ASIC in different platforms that have different requirements. For example, a conventional 20-port fibre channel switch cannot be used efficiently in a platform that does not need all the twenty ports. Hence, in conventional systems, the non-recurring cost of developing ASICs for different platforms is very high. This is commercially undesirable.
Therefore, there is a need for a method and system that can optimize power consumption so that a single ASIC can be used in different platforms.